North Koreans wave unification flags featuring one Korea as they bid farewell to South Korean priest and pro-unification activist Han Sang-ryol who crossed the border line at the truce village of Panmunjom in Paju, north of Seoul, on August 20, 2010 in this picture released by North Korea's KCNA news agency.

A sense of deja vu emanated from recent South-North border events: another imprisoned American left the North with a former U.S. president, and another South Korean was arrested upon return from the North for violating the National Security Law.

South Korea's prosecutors indicted Rev. Han Sang-ryul on Sept. 9, accusing him of praising North Korea and denouncing South Korea during a 70-day visit to the North, which began in June.

Few would dispute that Rev. Han, a man of faith, apparently maintained an unconscionable silence about the plight of his fellow Christians in North Korea during his visit. In doing so, he chose to ignore the North Korean government's brutal persecution of Christians and members of any other religious faith outside of state control.

Han's participation in such North Korean propaganda only discredits him. Frankly, it's hard to see why anyone would take him - or the vitriolic North Korean propaganda that spews forth daily from the KCNA - seriously.

Yet the South Korean government doesn't see it that way. Rev. Han was arrested as soon as he returned on Aug. 20, fresh from his send-off at a farewell party organized by the North Korean government, reportedly featuring 200 singing and chanting well-wishers.

By arresting him, South Korean authorities are clearly violating his right to peacefully exercise the right to freedom of expression. They are also rescuing Rev. Han's reputation by making him a martyr and increasing his value to North Korea's propagandists.

In late August, South Korea unapologetically blocked access to North Korea's propaganda-filled Facebook and Twitter accounts. The operators of Facebook later closed North Korea's account for still unexplained violations of its regulations.

The Twitter account is evidently still operating, though blocked in South Korea. The South Korean government has previously blocked virtually all other Web sites considered pro-North Korea.

These are just the latest episodes in the South Korean government's opportunistic use of the National Security Law to severely restrict the right to freedom of expression. Under the law, South Koreans are barred from meeting with North Koreans or visiting North Korea without state permission. They are forbidden from praising North Korea or disseminating North Korean propaganda.

The law clearly violates South Korea's international human-rights obligations.

Just as the government should not arrest people for joining a cult, neither should it incarcerate them for praising North Korea. Even when certain beliefs or thoughts appear wrong, bizarre or disturbing, propounding them should be protected as long as such speech does not amount to incitement, violence or other criminal action.

But according to the 2009 U.S. Department of State Human Rights Report, South Korea prosecuted 34 persons for violating the law in 2009, an increase from 27 in 2008.

The South Korean government should abolish or revise its National Security Law to protect freedom of expression, a basic human right enshrined in the Universal Declaration of Human Rights. South Korea is also a state party to the International Covenant on Civil and Political Rights. Article 19 of this convention stipulates that "everyone shall have the right to hold opinions without interference."

Although states can limit free expression in the interest of national security, they may do so only when "necessary in a democratic society" and for compelling reasons, such as protection of military secrets, not simply to avoid embarrassment or promote ideological solidarity.

One might argue that South Korea's arrest of Rev. Han and blocking information on the Internet pales in comparison with North Korea's approach to freedom of speech.

Very few people in North Korea have access to the Internet. And any North Korean who returned home after openly criticizing North Korea on a trip to the South would face horrifying consequences - dispatch to the infamous forced-labor camps as "traitors" or perhaps immediate execution.

But the fact that North Korea is one of the worst abusers of basic human rights and that it has kidnapped, detained and murdered many South Korean civilians, should not give South Korea carte blanche to limit South Koreans' freedom of opinion and expression. To set North Korea as the standard against which to measure civil rights is to set no standard at all for valuing human dignity and freedom.

South Korea should abolish or revise the National Security Law to ensure that it fully protects the freedom of opinion and expression. If ensuring such freedom means allowing South Koreans to see North Korea's propaganda or even to support Kim Jong-il, then so be it.

That is democracy.

And democracy is what South Koreans fought so hard and long to achieve in their decades of struggle under past military dictatorships.